AP Computer Science Principles Unit 3

Programming languages have some similarities and differences to the "natural" language you use in everyday speech. Select the two true statements about programming languages:

• Ambiguities in natural language necessitate the creation of programming languages for controlling a computer

• Compared to the number of words in a natural language, the number of defined words in a programming language is very small.

• The number of defined words in a programming language is about the same as the number of words in a natural language.

• There are typically many possible ways to interpret an instruction written in a programming language.

The next two questions use a robot in a grid of squares. The robot is represented as a triangle, which is initially facing up, towards the top of the grid. The robot is moved according to the instructions in the chart above.

Consider the following program which uses commands from the pseudocode described above.

REPEAT 4 TIMES {

MOVE_FORWARD()

MOVE_FORWARD()

MOVE_FORWARD()

ROTATE_RIGHT()

MOVE_FORWARD()

ROTATE_RIGHT()

MOVE_FORWARD()

ROTATE_RIGHT()

}

Which of the following images shows the path and ending location of the robot that will result from executing the code above. The starting location of the robot is shown as dotted triangle for cases where the robot does not start and end at the same location.

• 
• 
• 
• 
• 

Which of the following is NOT true about functions in programming?

• Functions are reusable programming abstractions.

• Functions help reduce the complexity of writing and maintaining programs.

• Functions cannot make calls to other functions within the same program.

• Functions help break a problem into logical chunks.

• Once defined, a function can be called many times from different parts of a program.

What is one important naming convention of functions?

• A function name should indicate how long the function takes to run.

• Two functions with similar behavior should be given identical names to indicate the relationship between them.

• A function name should be as descriptive as possible to indicate what the function does.

• Function names should be organized alphabetically.

• The function name should begin with a number that indicates the order in which it should be executed.

Which one of the following statements about functions is TRUE

• A function can change names over the course of a program.

• Code can be added or removed dynamically from a function while the program is running.

• Functions can be called using different names depending on where in the program they are called.

• Two functions can be given identical names as long as their code is identical.

• Two functions in a single program can have different names but contain identical code.

Which of the following will call the function drawStar?

• drawStar;

• drawStar();

• function drawStar (){

  for (var i=0; i<5; i++){

  moveForward(100);

  turnLeft(36);

  }

  }

• function drawStar;

• function drawStar();

Consider the following incorrect program, which is intended to move the robot around the perimeter of a grid, as indicated by the drawing above. The starting position and direction of the robot is indicated in the diagram.

Line 1: REPEAT 4 TIMES

Line 2: {

Line 3: MOVE_FORWARD()

Line 4: ROTATE_RIGHT()

Line 5: MOVE_FORWARD()

Line 6: MOVE_FORWARD()

Line 7: MOVE_FORWARD()

Line 8: MOVE_FORWARD()

Line 9: ROTATE_RIGHT()

Line 10: }

Given the options below, which lines should be removed so the program will work as intended?

• Line 3 and Line 4

• Lines 5, 6, 7, 8 and 9

• Line 8 and Line 9

• Line 9

For this scenario related to turtle drawing, indicate whether it is better to write a loop or a function (or a set of functions) to handle the task:

Drawing out the letters of a word "HELLO"

• Loop

• Function(s)

For this scenario related to turtle drawing, indicate whether it is better to write a loop or a function (or a set of functions) to handle the task:

Drawing 100 tiny dots in a line

• Loop

• Function(s)

For this scenario related to turtle drawing, indicate whether it is better to write a loop or a function (or a set of functions) to handle the task:

Drawing a circle of any size at any point on the screen

• Loop

• Function(s)